The video of them attempting to saw a hot dog (perfect simulated finger material) is impressive. The system detects that it’s cutting flesh, not wood, and stops and withdraws the blade before it has time to inflict more than a flesh wound.
The technology works by detecting differences in capacitance between wood and meat. In fact, if you have a trackpad-equipped notebook computer, you can try it out. Trackpads work by capacitive sensing, which is why a pencil won’t work for moving the pointer around.
In fact, I can’t help wondering whether it was discovered by an amputee realising that his prosthesis wouldn’t work on the trackpad...
SawStop deserve credit for this particular application of capacitive sensing. I really hope that this technology becomes pervasive in the near future.